Excited state dynamics of zinc and aluminum phthalocyanine carboxylates
- Idowu, Mopelola, Ogunsipe, Abimbola, Nyokong, Tebello
- Authors: Idowu, Mopelola , Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271228 , vital:54523 , xlink:href="https://doi.org/10.1016/j.saa.2007.01.025"
- Description: Photophysical parameters for zinc and aluminium tetracarboxylphthalocyanines (ZnTCPc and AlTCPc, respectively) and their octacarboxy substituted counterparts (ZnOCPc and AlOCPc) were studied. Data for the fluorescence quenching of the complexes by benzoquinone (BQ) were treated using the Stern–Volmer analysis, and the quenching was found to follow a diffusion-controlled (dynamic) bimolecular mechanism. Theoretical values of bimolecular rate constant for complex-BQ interactions were determined using the Stokes–Einstein–Smoluchowski model; and the values, together with the Stern–Volmer quenching constants were used in calculating the fluorescence lifetimes of the complexes. The thermodynamics of the MPc-BQ interaction, in terms of solvent reorientation energy is also discussed.
- Full Text:
- Date Issued: 2007
- Authors: Idowu, Mopelola , Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271228 , vital:54523 , xlink:href="https://doi.org/10.1016/j.saa.2007.01.025"
- Description: Photophysical parameters for zinc and aluminium tetracarboxylphthalocyanines (ZnTCPc and AlTCPc, respectively) and their octacarboxy substituted counterparts (ZnOCPc and AlOCPc) were studied. Data for the fluorescence quenching of the complexes by benzoquinone (BQ) were treated using the Stern–Volmer analysis, and the quenching was found to follow a diffusion-controlled (dynamic) bimolecular mechanism. Theoretical values of bimolecular rate constant for complex-BQ interactions were determined using the Stokes–Einstein–Smoluchowski model; and the values, together with the Stern–Volmer quenching constants were used in calculating the fluorescence lifetimes of the complexes. The thermodynamics of the MPc-BQ interaction, in terms of solvent reorientation energy is also discussed.
- Full Text:
- Date Issued: 2007
Exploring the options for fuelwood policies to support poverty alleviation policies: Evolving dimensions in South Africa
- Shackleton, Charlie M, Buiten, Erik, Annecke, W, Banks, D, Bester, J, Everson, T, Fabricius, Christo, Ham, C, Kees, M, Modise, M, Phago, M, Prasad, Gisela, Twine, Wayne, Underwood, Michael, von Maltitz, Graham, Wentzel, P
- Authors: Shackleton, Charlie M , Buiten, Erik , Annecke, W , Banks, D , Bester, J , Everson, T , Fabricius, Christo , Ham, C , Kees, M , Modise, M , Phago, M , Prasad, Gisela , Twine, Wayne , Underwood, Michael , von Maltitz, Graham , Wentzel, P
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181213 , vital:43709 , xlink:href="https://doi.org/10.1080/14728028.2007.9752604"
- Description: Access to secure and affordable energy supplies is widely acknowledged as a critical foundation for sustainable development; inadequate access exacerbates household poverty. In the developing world poor households are frequently reliant upon fuel wood for all or most of their energy needs. However, national poverty alleviation policies commonly do not consider fuelwood within their strategies, and similarly, energy policies rarely consider the poverty alleviation potential of a comprehensive fuelwood strategy. Consequently, synergies between poverty alleviation and energy policies—with fuelwood (and its derivates) as the bridge—are needed. This paper discusses this potential using South Africa as a case example. The current policy environment that either favours or hinders a linkage between the poverty and energy sectors and policy options and strategies available to develop such links, are discussed.
- Full Text:
- Date Issued: 2007
- Authors: Shackleton, Charlie M , Buiten, Erik , Annecke, W , Banks, D , Bester, J , Everson, T , Fabricius, Christo , Ham, C , Kees, M , Modise, M , Phago, M , Prasad, Gisela , Twine, Wayne , Underwood, Michael , von Maltitz, Graham , Wentzel, P
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181213 , vital:43709 , xlink:href="https://doi.org/10.1080/14728028.2007.9752604"
- Description: Access to secure and affordable energy supplies is widely acknowledged as a critical foundation for sustainable development; inadequate access exacerbates household poverty. In the developing world poor households are frequently reliant upon fuel wood for all or most of their energy needs. However, national poverty alleviation policies commonly do not consider fuelwood within their strategies, and similarly, energy policies rarely consider the poverty alleviation potential of a comprehensive fuelwood strategy. Consequently, synergies between poverty alleviation and energy policies—with fuelwood (and its derivates) as the bridge—are needed. This paper discusses this potential using South Africa as a case example. The current policy environment that either favours or hinders a linkage between the poverty and energy sectors and policy options and strategies available to develop such links, are discussed.
- Full Text:
- Date Issued: 2007
Exploring the practical adequacy of the normative framework guiding South Africa’s National Curriculum Statement
- Lotz-Sisitka, Heila, Schudel, Ingrid J
- Authors: Lotz-Sisitka, Heila , Schudel, Ingrid J
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/294386 , vital:57217 , xlink:href="https://doi.org/10.1080/13504620701284860"
- Description: This article examines the practical adequacy of the recent defining of a normative framework for the South African National Curriculum Statement that focuses on the relationship between human rights, social justice and a healthy environment. This politically framed and socially critical normative framework has developed in response to socio‐political and socio‐ecological histories in post‐apartheid curriculum transformation processes. The article critically considers the process of working with a normative framework in the defining of environmental education teaching and learning interactions, and seeks not only to explore the policy discourse critically, but also to explore what it is about the world that makes it work in different ways. Drawing on Sayer’s perspectives on the possibilities of enabling ‘situated universalism’ as a form of normative theory, and case‐based data from a teacher professional development programme in the Makana District (where the authors live and work), the article probes the relationship between the establishment of a ‘universalising’ normative framework to guide national curriculum, and situated engagements with this framework in/as democratic process. In this process it questions whether educators should adopt the ‘norms’ as presented by society and simply universalize and implement them as prescribed by curriculum statements, or whether educators should adopt the strategies of postmodernists and reduce normative frameworks to relations of power situated in particular contexts.
- Full Text:
- Date Issued: 2007
- Authors: Lotz-Sisitka, Heila , Schudel, Ingrid J
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/294386 , vital:57217 , xlink:href="https://doi.org/10.1080/13504620701284860"
- Description: This article examines the practical adequacy of the recent defining of a normative framework for the South African National Curriculum Statement that focuses on the relationship between human rights, social justice and a healthy environment. This politically framed and socially critical normative framework has developed in response to socio‐political and socio‐ecological histories in post‐apartheid curriculum transformation processes. The article critically considers the process of working with a normative framework in the defining of environmental education teaching and learning interactions, and seeks not only to explore the policy discourse critically, but also to explore what it is about the world that makes it work in different ways. Drawing on Sayer’s perspectives on the possibilities of enabling ‘situated universalism’ as a form of normative theory, and case‐based data from a teacher professional development programme in the Makana District (where the authors live and work), the article probes the relationship between the establishment of a ‘universalising’ normative framework to guide national curriculum, and situated engagements with this framework in/as democratic process. In this process it questions whether educators should adopt the ‘norms’ as presented by society and simply universalize and implement them as prescribed by curriculum statements, or whether educators should adopt the strategies of postmodernists and reduce normative frameworks to relations of power situated in particular contexts.
- Full Text:
- Date Issued: 2007
Factors affecting ethical judgement of South African chartered accountants
- Maree, Kevin W, Radloff, Sarah E
- Authors: Maree, Kevin W , Radloff, Sarah E
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: Article
- Identifier: vital:6073 , http://hdl.handle.net/10962/d1001647 , ISSN 1022-2529 , http://0-dx.doi.org.wam.seals.ac.za/10.1108/10222529200700001
- Description: The start of the twenty-first century was marred by a spate of company collapses that involved fraudulent accounting activity. In many cases, company executives, many of whom belonged to the accounting profession, perpetrated the fraud. As a result, internationally, the accounting profession has suffered an enormous loss of goodwill, and its reputation as a profession with integrity has been severely harmed. Accounting professionals are no longer accorded the high regard they commanded in the past. The consequences for the profession have been far-reaching: accounting now faces a long, uphill battle to restore its reputation and to regain the trust of the international business community. This study replicates two famous international studies in the South African context. The focus of the study was to establish whether factors such as the Code of Professional Conduct of the South African Institute of Chartered Accountants (SAICA), the corporate ethical environment and their age influence the ethical judgement of individual accountants. The first such study was conducted in the United States of America (USA), and it was followed by similar research in Turkey. The results of these two studies suggested very different factors that could influence accountants' ethical judgement. The study reported in this article investigated South African chartered accountants; and its results were similar to those obtained in the US study.
- Full Text:
- Date Issued: 2007
- Authors: Maree, Kevin W , Radloff, Sarah E
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: Article
- Identifier: vital:6073 , http://hdl.handle.net/10962/d1001647 , ISSN 1022-2529 , http://0-dx.doi.org.wam.seals.ac.za/10.1108/10222529200700001
- Description: The start of the twenty-first century was marred by a spate of company collapses that involved fraudulent accounting activity. In many cases, company executives, many of whom belonged to the accounting profession, perpetrated the fraud. As a result, internationally, the accounting profession has suffered an enormous loss of goodwill, and its reputation as a profession with integrity has been severely harmed. Accounting professionals are no longer accorded the high regard they commanded in the past. The consequences for the profession have been far-reaching: accounting now faces a long, uphill battle to restore its reputation and to regain the trust of the international business community. This study replicates two famous international studies in the South African context. The focus of the study was to establish whether factors such as the Code of Professional Conduct of the South African Institute of Chartered Accountants (SAICA), the corporate ethical environment and their age influence the ethical judgement of individual accountants. The first such study was conducted in the United States of America (USA), and it was followed by similar research in Turkey. The results of these two studies suggested very different factors that could influence accountants' ethical judgement. The study reported in this article investigated South African chartered accountants; and its results were similar to those obtained in the US study.
- Full Text:
- Date Issued: 2007
Factors influencing prices of medicinal plants traded in the Lowveld, South Africa
- Botha, Jenny, Witkowski, Ed T F, Shackleton, Charlie M
- Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181257 , vital:43713 , xlink:href="https://doi.org/10.1080/13504500709469745"
- Description: There has been limited research into pricing and consumer behaviour in the informal sector, an understanding of which is critical to effective management of extensively traded wildlife resources. This paper explores factors influencing prices of wild-collected medicinal plants traded in the Lowveld, South Africa. Resource management decisions relating to medicinal plants are often based on the high price/kg values of certain species, and the assumption that there is an inverse relationship between the availability of products and prices. Despite the high-utility value of these plants, subsistence consumers have historically paid low prices for products. In this study, price/kg fluctuated widely, as did market players' perceptions of species availability and consumer demand. Unit prices were low, with a few exceptions. There was no relationship between prices and perceptions of species availability. No relationship was found between prices and consumer demand in one study area, although there was a non-significant relationship in the other. The size of products was the main determinant of price. Consumers were prepared to pay higher prices for certain species, e.g.those used to treat children, those considered highly dangerous (culturally) to collect, or those used for anti-social purposes.
- Full Text:
- Date Issued: 2007
- Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181257 , vital:43713 , xlink:href="https://doi.org/10.1080/13504500709469745"
- Description: There has been limited research into pricing and consumer behaviour in the informal sector, an understanding of which is critical to effective management of extensively traded wildlife resources. This paper explores factors influencing prices of wild-collected medicinal plants traded in the Lowveld, South Africa. Resource management decisions relating to medicinal plants are often based on the high price/kg values of certain species, and the assumption that there is an inverse relationship between the availability of products and prices. Despite the high-utility value of these plants, subsistence consumers have historically paid low prices for products. In this study, price/kg fluctuated widely, as did market players' perceptions of species availability and consumer demand. Unit prices were low, with a few exceptions. There was no relationship between prices and perceptions of species availability. No relationship was found between prices and consumer demand in one study area, although there was a non-significant relationship in the other. The size of products was the main determinant of price. Consumers were prepared to pay higher prices for certain species, e.g.those used to treat children, those considered highly dangerous (culturally) to collect, or those used for anti-social purposes.
- Full Text:
- Date Issued: 2007
Immobilization of tetra-amine substituted metallophthalocyanines at gold surfaces modified with mercaptopropionic acid or DTSP-SAMs
- Matemadombo, Fungisai, Westbroek, Philippe, Nyokong, Tebello, Ozoemena, Kenneth, De Clerck, Karen, Kiekens, Paul
- Authors: Matemadombo, Fungisai , Westbroek, Philippe , Nyokong, Tebello , Ozoemena, Kenneth , De Clerck, Karen , Kiekens, Paul
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283924 , vital:56003 , xlink:href="https://doi.org/10.1016/j.electacta.2006.08.027"
- Description: This paper shows that amine substituted cobalt phthalocyanine (CoTAPc) can be deposited on gold surfaces by using an interconnecting layer of a self-assembled monolayer (SAM) of mercaptopropionic acid or Lomant's reagent (dithiobis(N-succinimidyl propionate) (DTSP)). In both cases the new bond formed is obtained by the creation of an amide. The layers were characterized by electrochemistry and showed high coverage fractions (near 100%). Reductive and oxidative desorption of the SAMs limit the useful potential window from −0.6 to +0.5 V versus Ag|AgCl. The SAM-CoTAPc layers show electrocatalytic activities towards oxygen reduction through the Co(I) central metal ion. The amount of CoTAPc molecules deposited (obtained from the Co central metal ion activity in nitrogen purged solutions) revealed that the CoTAPc molecules are bonded in a perpendicular manner at the surface. Taking into account a surface of 200 Å2 for a flatly bonded MPc, this should result in a four times less amount of deposited CoTAPc compared to the experimental value obtained. Both methods showed good results and promising long-term stability and will be interesting tools for further research in surface modification and sensor development.
- Full Text:
- Date Issued: 2007
- Authors: Matemadombo, Fungisai , Westbroek, Philippe , Nyokong, Tebello , Ozoemena, Kenneth , De Clerck, Karen , Kiekens, Paul
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283924 , vital:56003 , xlink:href="https://doi.org/10.1016/j.electacta.2006.08.027"
- Description: This paper shows that amine substituted cobalt phthalocyanine (CoTAPc) can be deposited on gold surfaces by using an interconnecting layer of a self-assembled monolayer (SAM) of mercaptopropionic acid or Lomant's reagent (dithiobis(N-succinimidyl propionate) (DTSP)). In both cases the new bond formed is obtained by the creation of an amide. The layers were characterized by electrochemistry and showed high coverage fractions (near 100%). Reductive and oxidative desorption of the SAMs limit the useful potential window from −0.6 to +0.5 V versus Ag|AgCl. The SAM-CoTAPc layers show electrocatalytic activities towards oxygen reduction through the Co(I) central metal ion. The amount of CoTAPc molecules deposited (obtained from the Co central metal ion activity in nitrogen purged solutions) revealed that the CoTAPc molecules are bonded in a perpendicular manner at the surface. Taking into account a surface of 200 Å2 for a flatly bonded MPc, this should result in a four times less amount of deposited CoTAPc compared to the experimental value obtained. Both methods showed good results and promising long-term stability and will be interesting tools for further research in surface modification and sensor development.
- Full Text:
- Date Issued: 2007
Inetvis: a graphical aid for the detection and visualisation of network scans
- Irwin, Barry V W, van Riel, Jean-Pierre
- Authors: Irwin, Barry V W , van Riel, Jean-Pierre
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430381 , vital:72687 , https://www.cs.ru.ac.za/research/g02V2468/publications/Irwin-VizSEC2007_draft.pdf
- Description: This paper presents an investigative analysis of network scans and scan detection algorithms. Visualisation is employed to review network telescope traffic and identify incidents of scan activity. Some of the identified phenomena appear to be novel forms of host discovery. The scan detection algorithms of Snort and Bro are critiqued by comparing the visualised scans with alert output. Where human assessment disa-grees with the alert output, explanations are sought after by analysing the detection algorithms. The algorithms of the Snort and Bro intrusion detection systems are based on counting unique connection attempts to destination addresses and ports. For Snort, notable false positive and false negative cases result due to a grossly oversimplified method of counting unique destination addresses and ports.
- Full Text:
- Date Issued: 2007
- Authors: Irwin, Barry V W , van Riel, Jean-Pierre
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430381 , vital:72687 , https://www.cs.ru.ac.za/research/g02V2468/publications/Irwin-VizSEC2007_draft.pdf
- Description: This paper presents an investigative analysis of network scans and scan detection algorithms. Visualisation is employed to review network telescope traffic and identify incidents of scan activity. Some of the identified phenomena appear to be novel forms of host discovery. The scan detection algorithms of Snort and Bro are critiqued by comparing the visualised scans with alert output. Where human assessment disa-grees with the alert output, explanations are sought after by analysing the detection algorithms. The algorithms of the Snort and Bro intrusion detection systems are based on counting unique connection attempts to destination addresses and ports. For Snort, notable false positive and false negative cases result due to a grossly oversimplified method of counting unique destination addresses and ports.
- Full Text:
- Date Issued: 2007
Insights into the surface and redox properties of single-walled carbon nanotube—cobalt (II) tetra-aminophthalocyanine self-assembled on gold electrode
- Ozoemena, Kenneth I, Nyokong, Tebello, Nkosi, Duduzile, Chambrier, Isabelle, Cook, Michael J
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello , Nkosi, Duduzile , Chambrier, Isabelle , Cook, Michael J
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281258 , vital:55707 , xlink:href="https://doi.org/10.1016/j.electacta.2006.11.039"
- Description: This paper describes for the first time the electrochemical properties of redox-active self-assembled films of single-walled carbon nanotubes (SWCNTs) coordinated to cobalt(II)tetra-aminophthalocyanine (CoTAPc) by sequential self-assembly onto a preformed aminoethanethiol (AET) self-assembled monolayer (SAM) on a gold electrode. Both redox-active SAMs (Au-AET-SWCNT and Au-AET-SWCNT-CoTAPc) exhibited reversible electrochemistry in aqueous (phosphate buffer) solution. X-ray photoelectron spectroscopy (XPS) confirmed the appearance on the gold surface of the various elements found on the SAMs. Atomic force microscopy (AFM) images prove, corroborating the estimated electrochemical surface concentrations, that these SAMs lie normal to the gold surface. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)6]3−/4− as a redox probe revealed that the Au-AET-SWCNT-CoTAPc showed much lower (∼10 times) electron-transfer resistance (Ret) and much higher (∼10 times) apparent electron-transfer rate constant (kapp) compared to the Au-AET-SWCNT SAM. Interestingly, a preliminary electrocatalytic investigation showed that both SAMs exhibit comparable electrocatalytic responses towards the detection of dopamine in pH 7.4 phosphate buffer solutions (PBS). The electrochemical studies (cyclic voltammetry (CV) and EIS) prove that SWCNT greatly improves the electronic communication between CoTAPc and the Au electrode surface.
- Full Text:
- Date Issued: 2007
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello , Nkosi, Duduzile , Chambrier, Isabelle , Cook, Michael J
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281258 , vital:55707 , xlink:href="https://doi.org/10.1016/j.electacta.2006.11.039"
- Description: This paper describes for the first time the electrochemical properties of redox-active self-assembled films of single-walled carbon nanotubes (SWCNTs) coordinated to cobalt(II)tetra-aminophthalocyanine (CoTAPc) by sequential self-assembly onto a preformed aminoethanethiol (AET) self-assembled monolayer (SAM) on a gold electrode. Both redox-active SAMs (Au-AET-SWCNT and Au-AET-SWCNT-CoTAPc) exhibited reversible electrochemistry in aqueous (phosphate buffer) solution. X-ray photoelectron spectroscopy (XPS) confirmed the appearance on the gold surface of the various elements found on the SAMs. Atomic force microscopy (AFM) images prove, corroborating the estimated electrochemical surface concentrations, that these SAMs lie normal to the gold surface. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)6]3−/4− as a redox probe revealed that the Au-AET-SWCNT-CoTAPc showed much lower (∼10 times) electron-transfer resistance (Ret) and much higher (∼10 times) apparent electron-transfer rate constant (kapp) compared to the Au-AET-SWCNT SAM. Interestingly, a preliminary electrocatalytic investigation showed that both SAMs exhibit comparable electrocatalytic responses towards the detection of dopamine in pH 7.4 phosphate buffer solutions (PBS). The electrochemical studies (cyclic voltammetry (CV) and EIS) prove that SWCNT greatly improves the electronic communication between CoTAPc and the Au electrode surface.
- Full Text:
- Date Issued: 2007
Learning in a Changing World
- Lotz-Sisitka, Heila, O'Donoghue, Rob, Robottom, Ian
- Authors: Lotz-Sisitka, Heila , O'Donoghue, Rob , Robottom, Ian
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182679 , vital:43853 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122733 "
- Description: The year 2007 is a significant year for environmental education. It marks 30 years since the first internationally agreed principles of environmental education were developed at Tbilisi, commonly known as the Tbilisi Principles. It is also the year in which human beings apparently are finally ‘waking up’ to the fact that human-induced environmental change is causing impacts which are infinitely complex and difficult to resolve. This year, through various highly publicised and politicised events, people have begun to recognise that it is getting hot on planet Earth, and that the associated social, economic and environmental costs are profoundly disturbing. The Stern Review and the UN Intergovernmental Panel on Climate Change both firmly indicated that human-induced environmental change will threaten human economies and security in ways that are unprecedented in human history. Southern Africa, where this special edition of the EEASA Journal is being produced to coincide with the 25th anniversary of the existence of the Environmental Education Association of Southern Africa, and the hosting of the 4th World Environmental Education Congress, is one of the areas most vulnerable to the impacts of climate change. More than 70% of the people in southern Africa live in rural areas, and depend directly on natural resources for their livelihood and food security, making environment (and environmental education processes) a central concern in development discussions in the region. Patterns of global inequality are pronounced in the region, which has some of the poorest countries in the world. Out of its 25-year history, EEASA and its members, along with colleagues around the world, continue to seek ways of educating and empowering people to successfully participate in resolving environmental issues and create more sustainable and socially just living patterns. In drawing attention to our constant need to learn how to improve our understandings of environmental education and learning as the world around us changes, the World Environmental Education Congress organising committee chose to profile the question of ‘Learning in a Changing World’, by making this the theme of the Congress.
- Full Text:
- Date Issued: 2007
- Authors: Lotz-Sisitka, Heila , O'Donoghue, Rob , Robottom, Ian
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182679 , vital:43853 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122733 "
- Description: The year 2007 is a significant year for environmental education. It marks 30 years since the first internationally agreed principles of environmental education were developed at Tbilisi, commonly known as the Tbilisi Principles. It is also the year in which human beings apparently are finally ‘waking up’ to the fact that human-induced environmental change is causing impacts which are infinitely complex and difficult to resolve. This year, through various highly publicised and politicised events, people have begun to recognise that it is getting hot on planet Earth, and that the associated social, economic and environmental costs are profoundly disturbing. The Stern Review and the UN Intergovernmental Panel on Climate Change both firmly indicated that human-induced environmental change will threaten human economies and security in ways that are unprecedented in human history. Southern Africa, where this special edition of the EEASA Journal is being produced to coincide with the 25th anniversary of the existence of the Environmental Education Association of Southern Africa, and the hosting of the 4th World Environmental Education Congress, is one of the areas most vulnerable to the impacts of climate change. More than 70% of the people in southern Africa live in rural areas, and depend directly on natural resources for their livelihood and food security, making environment (and environmental education processes) a central concern in development discussions in the region. Patterns of global inequality are pronounced in the region, which has some of the poorest countries in the world. Out of its 25-year history, EEASA and its members, along with colleagues around the world, continue to seek ways of educating and empowering people to successfully participate in resolving environmental issues and create more sustainable and socially just living patterns. In drawing attention to our constant need to learn how to improve our understandings of environmental education and learning as the world around us changes, the World Environmental Education Congress organising committee chose to profile the question of ‘Learning in a Changing World’, by making this the theme of the Congress.
- Full Text:
- Date Issued: 2007
Mechanisms for multimodality: taking fiction to another dimension
- Glass, Kevin R, Bangay, Shaun D, Alcock, Bruce
- Authors: Glass, Kevin R , Bangay, Shaun D , Alcock, Bruce
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433226 , vital:72953 , https://doi.org/10.1145/1294685.1294708
- Description: We present methods for automatically constructing representations of fiction books in a range of modalities: audibly, graphically and as 3D virtual environments. The correspondence between the sequential ordering of events against the order of events presented in the text is used to correctly resolve the dynamic interactions for each representation. Synthesised audio created from the fiction text is used to calibrate the base time-line against which the other forms of media are correctly aligned. The audio stream is based on speech synthesis using the text of the book, and is enhanced using distinct voices for the different characters in a book. Sound effects are included automatically. The graphical representation represents the text (as subtitles), identifies active characters and provides visual feedback of the content of the story. Dynamic virtual environments conform to the constraints implied by the story, and are used as a source of further visual content. These representations are all aligned to a common time-line, and combined using sequencing facilities to provide a multimodal version of the original text.
- Full Text:
- Date Issued: 2007
- Authors: Glass, Kevin R , Bangay, Shaun D , Alcock, Bruce
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433226 , vital:72953 , https://doi.org/10.1145/1294685.1294708
- Description: We present methods for automatically constructing representations of fiction books in a range of modalities: audibly, graphically and as 3D virtual environments. The correspondence between the sequential ordering of events against the order of events presented in the text is used to correctly resolve the dynamic interactions for each representation. Synthesised audio created from the fiction text is used to calibrate the base time-line against which the other forms of media are correctly aligned. The audio stream is based on speech synthesis using the text of the book, and is enhanced using distinct voices for the different characters in a book. Sound effects are included automatically. The graphical representation represents the text (as subtitles), identifies active characters and provides visual feedback of the content of the story. Dynamic virtual environments conform to the constraints implied by the story, and are used as a source of further visual content. These representations are all aligned to a common time-line, and combined using sequencing facilities to provide a multimodal version of the original text.
- Full Text:
- Date Issued: 2007
Microwave synthesis and photophysics of new tetrasulfonated tin (II) macrocycles
- Khene, Samson, Ogunsipe, Abimbola, Antunes, Edith M, Nyokong, Tebello
- Authors: Khene, Samson , Ogunsipe, Abimbola , Antunes, Edith M , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281269 , vital:55708 , xlink:href="https://doi.org/10.1142/S108842460700014X"
- Description: This work reports on the microwave synthesis of tetrasulfonated tin phthalocyanine and tetrasulfonated tin α,β,γ-tetrabenzcorrole. The latter was only formed at low ratios (more than 1:8) of 4-sulfophthalic acid to urea. Both complexes are aggregated in aqueous media, but can be partly or fully disaggregated by the addition of Triton X-100. The α,β,γ-tetrabenzcorrole complex has lower triplet life times and yields, while the binding constant and quenching (of bovine serum albumin) constant are lower for α,β,γ-tetrabenzcorrole compared to tetrasulfonated tin phthalocyanine.
- Full Text:
- Date Issued: 2007
- Authors: Khene, Samson , Ogunsipe, Abimbola , Antunes, Edith M , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281269 , vital:55708 , xlink:href="https://doi.org/10.1142/S108842460700014X"
- Description: This work reports on the microwave synthesis of tetrasulfonated tin phthalocyanine and tetrasulfonated tin α,β,γ-tetrabenzcorrole. The latter was only formed at low ratios (more than 1:8) of 4-sulfophthalic acid to urea. Both complexes are aggregated in aqueous media, but can be partly or fully disaggregated by the addition of Triton X-100. The α,β,γ-tetrabenzcorrole complex has lower triplet life times and yields, while the binding constant and quenching (of bovine serum albumin) constant are lower for α,β,γ-tetrabenzcorrole compared to tetrasulfonated tin phthalocyanine.
- Full Text:
- Date Issued: 2007
Negotiating the Good Life
- Authors: Tabensky, Pedro
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/305688 , vital:58604 , xlink:href="http://10.1007/s10677-006-9030-x"
- Description: Book Review: Mark A. Young asks: “Is there a problem with community in America?” (p. 1). Agreeing with Robert Putnam’s views, embodied in Bowling Alone: The Collapse and Revival of American Community (New York: Touchstone Press, 2000), regarding the breakdown of communal values in the US, but not with his nostalgic recommendations regarding the ‘good old days’ of univocal homogenous communities, Young proposes an alternative solution to Putnam’s, starting from Aristotle’s sophisticated account of the self/community relation and drawing important insights from Alasdair MacIntyre, Charles Taylor, Amitai Etzione, Paul Ricoeur, Michael Sandel and especially Hannah Arendt.
- Full Text:
- Date Issued: 2007
- Authors: Tabensky, Pedro
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/305688 , vital:58604 , xlink:href="http://10.1007/s10677-006-9030-x"
- Description: Book Review: Mark A. Young asks: “Is there a problem with community in America?” (p. 1). Agreeing with Robert Putnam’s views, embodied in Bowling Alone: The Collapse and Revival of American Community (New York: Touchstone Press, 2000), regarding the breakdown of communal values in the US, but not with his nostalgic recommendations regarding the ‘good old days’ of univocal homogenous communities, Young proposes an alternative solution to Putnam’s, starting from Aristotle’s sophisticated account of the self/community relation and drawing important insights from Alasdair MacIntyre, Charles Taylor, Amitai Etzione, Paul Ricoeur, Michael Sandel and especially Hannah Arendt.
- Full Text:
- Date Issued: 2007
Novel gallium (III) phthalocyanine derivatives–Synthesis, photophysics and photochemistry
- Chauke, Vongani, Ogunsipe, Abimbola, Durmus, Mahmut, Nyokong, Tebello
- Authors: Chauke, Vongani , Ogunsipe, Abimbola , Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283118 , vital:55912 , xlink:href="https://doi.org/10.1016/j.poly.2007.01.016"
- Description: The syntheses of gallium(III) chloride phthalocyanine {(Cl)GaPc}, octaphenoxyphthalocyaninato gallium(III) chloride {(Cl)GaOPPc} and octakis(4-tert-butylphenoxy)phthalocyaninato gallium(III) chloride {(Cl)GaOTBPPc}; as well as their photophysical and photochemical parameters are hereby presented. Fluorescence quantum yields do not vary much among the three metallophthalocyanines (MPcs); therefore it was concluded that the effect of the substituents is not significant amongst (Cl)GaPc, (Cl)GaOPPc and (Cl)GaOTBPPc. Solvents effects, however, had an effect on the results. Triplet quantum yields were found to be lower in DMSO than in DMF and toluene. The rate constants for fluorescence, intersystem crossing and internal conversion as well as fluorescence and triplet lifetimes are reported. We have also reported photodegradation and singlet oxygen quantum yields. There was no clear correlation between the later parameters. It was, however, established that the three MPcs were stable.
- Full Text:
- Date Issued: 2007
- Authors: Chauke, Vongani , Ogunsipe, Abimbola , Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283118 , vital:55912 , xlink:href="https://doi.org/10.1016/j.poly.2007.01.016"
- Description: The syntheses of gallium(III) chloride phthalocyanine {(Cl)GaPc}, octaphenoxyphthalocyaninato gallium(III) chloride {(Cl)GaOPPc} and octakis(4-tert-butylphenoxy)phthalocyaninato gallium(III) chloride {(Cl)GaOTBPPc}; as well as their photophysical and photochemical parameters are hereby presented. Fluorescence quantum yields do not vary much among the three metallophthalocyanines (MPcs); therefore it was concluded that the effect of the substituents is not significant amongst (Cl)GaPc, (Cl)GaOPPc and (Cl)GaOTBPPc. Solvents effects, however, had an effect on the results. Triplet quantum yields were found to be lower in DMSO than in DMF and toluene. The rate constants for fluorescence, intersystem crossing and internal conversion as well as fluorescence and triplet lifetimes are reported. We have also reported photodegradation and singlet oxygen quantum yields. There was no clear correlation between the later parameters. It was, however, established that the three MPcs were stable.
- Full Text:
- Date Issued: 2007
Photocatalysis of 4-nitrophenol using zinc phthalocyanine complexes
- Marais, Eloïse, Klein, Rosalyn, Antunes, Edith M, Nyokong, Tebello
- Authors: Marais, Eloïse , Klein, Rosalyn , Antunes, Edith M , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281286 , vital:55709 , xlink:href="https://doi.org/10.1016/j.molcata.2006.07.055"
- Description: Photodegradation of 4-nitrophenol (4-Np) in the presence of zinc tetrasulfophthalocyanine (ZnPcS4), zinc octacarboxyphthalocyanine (ZnPc(COOH)8) and a sulfonated ZnPc containing a mixture of differently sulfonated derivatives (ZnPcSmix), as photocatalysts is reported. ZnPcSmix is the most effective catalyst in terms of a high quantum yield for 4-Np degradation and the stability of the catalyst. However ZnPc(COOH)8 degrades readily during the catalysis, but it has a higher quantum yield (Φ4-Np) for 4-Np degradation than the rest of the complexes. The Φ4-Np values were closely related to the singlet oxygen quantum yields ΦΔ and hence aggregation. The rate constants for the reaction with 4-Np were kr = 0.67 × 106 mol−1 dm3 s−1 for ZnPcSmix and 2.8 × 108 mol−1 dm3 s−1 for ZnPc(COOH)8.
- Full Text:
- Date Issued: 2007
- Authors: Marais, Eloïse , Klein, Rosalyn , Antunes, Edith M , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281286 , vital:55709 , xlink:href="https://doi.org/10.1016/j.molcata.2006.07.055"
- Description: Photodegradation of 4-nitrophenol (4-Np) in the presence of zinc tetrasulfophthalocyanine (ZnPcS4), zinc octacarboxyphthalocyanine (ZnPc(COOH)8) and a sulfonated ZnPc containing a mixture of differently sulfonated derivatives (ZnPcSmix), as photocatalysts is reported. ZnPcSmix is the most effective catalyst in terms of a high quantum yield for 4-Np degradation and the stability of the catalyst. However ZnPc(COOH)8 degrades readily during the catalysis, but it has a higher quantum yield (Φ4-Np) for 4-Np degradation than the rest of the complexes. The Φ4-Np values were closely related to the singlet oxygen quantum yields ΦΔ and hence aggregation. The rate constants for the reaction with 4-Np were kr = 0.67 × 106 mol−1 dm3 s−1 for ZnPcSmix and 2.8 × 108 mol−1 dm3 s−1 for ZnPc(COOH)8.
- Full Text:
- Date Issued: 2007
Photochemistry, photophysics and nonlinear optical parameters of phenoxy and tert-butylphenoxy substituted indium (III) phthalocyanines
- Chauke, Vongani, Durmus, Mahmut, Nyokong, Tebello
- Authors: Chauke, Vongani , Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268823 , vital:54235 , xlink:href="https://doi.org/10.1016/j.jphotochem.2007.05.022"
- Description: This work hereby presents the syntheses, photochemistry and photophysics of octaphenoxy ((Cl)InOPPc) and octakis(4-tert-butylphenoxy)chloroindium ((Cl)InOTBPPc) phthalocyanines. Calculated nonlinear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. Fluorescence quantum yields do not vary much between (Cl)InOPPc and (Cl)InOTBPPc complexes in different solvents. High quantum yields of triplet state (ΦT ranging from 0.70 to 0.91 in dimethysulphoxide, DMSO) and singlet oxygen generation (ΦΔ, ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50–60 μs were obtained in DMSO). The optical limiting threshold intensity (Ilim) for the InPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The latter were found to be better optical limiters.
- Full Text:
- Date Issued: 2007
- Authors: Chauke, Vongani , Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268823 , vital:54235 , xlink:href="https://doi.org/10.1016/j.jphotochem.2007.05.022"
- Description: This work hereby presents the syntheses, photochemistry and photophysics of octaphenoxy ((Cl)InOPPc) and octakis(4-tert-butylphenoxy)chloroindium ((Cl)InOTBPPc) phthalocyanines. Calculated nonlinear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. Fluorescence quantum yields do not vary much between (Cl)InOPPc and (Cl)InOTBPPc complexes in different solvents. High quantum yields of triplet state (ΦT ranging from 0.70 to 0.91 in dimethysulphoxide, DMSO) and singlet oxygen generation (ΦΔ, ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50–60 μs were obtained in DMSO). The optical limiting threshold intensity (Ilim) for the InPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The latter were found to be better optical limiters.
- Full Text:
- Date Issued: 2007
Photochemistry, photophysics and nonlinear optical parameters of phenoxy and tert-butylphenoxy substituted indium (III) phthalocyanines
- Chauke, Vongani, Durmus, Mahmut, Nyokong, Tebello
- Authors: Chauke, Vongani , Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268787 , vital:54232 , xlink:href="https://doi.org/10.1016/j.jphotochem.2007.05.022"
- Description: This work hereby presents the syntheses, photochemistry and photophysics of octaphenoxy ((Cl)InOPPc) and octakis(4-tert-butylphenoxy)chloroindium ((Cl)InOTBPPc) phthalocyanines. Calculated nonlinear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. Fluorescence quantum yields do not vary much between (Cl)InOPPc and (Cl)InOTBPPc complexes in different solvents. High quantum yields of triplet state (ΦT ranging from 0.70 to 0.91 in dimethysulphoxide, DMSO) and singlet oxygen generation (ΦΔ, ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50–60 μs were obtained in DMSO). The optical limiting threshold intensity (Ilim) for the InPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The latter were found to be better optical limiters.
- Full Text:
- Date Issued: 2007
- Authors: Chauke, Vongani , Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268787 , vital:54232 , xlink:href="https://doi.org/10.1016/j.jphotochem.2007.05.022"
- Description: This work hereby presents the syntheses, photochemistry and photophysics of octaphenoxy ((Cl)InOPPc) and octakis(4-tert-butylphenoxy)chloroindium ((Cl)InOTBPPc) phthalocyanines. Calculated nonlinear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. Fluorescence quantum yields do not vary much between (Cl)InOPPc and (Cl)InOTBPPc complexes in different solvents. High quantum yields of triplet state (ΦT ranging from 0.70 to 0.91 in dimethysulphoxide, DMSO) and singlet oxygen generation (ΦΔ, ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50–60 μs were obtained in DMSO). The optical limiting threshold intensity (Ilim) for the InPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The latter were found to be better optical limiters.
- Full Text:
- Date Issued: 2007
Photophysical and photochemical properties of zinc and aluminum phthalocyanines in the presence of magnetic fluid
- Idowu, Mopelola, Nyokong, Tebello
- Authors: Idowu, Mopelola , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281298 , vital:55710 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.12.013"
- Description: The effect of magnetic fluid (MF) on the photophysical and photochemical parameters of zinc and aluminum phthalocyanines are reported. The complexes studied are zinc (II) phthalocyanine (ZnPc), chloroaluminum phthalocyanine ((Cl)AlPc) and tetrasulfonated aluminum phthalocyanine ((Cl)AlTSPc). The parameters are studied in dimethylsulfoxide (DMSO) for all complexes and also in aqueous media for (Cl)AlTSPc. The triplet lifetimes for (Cl)AlTSPc and ZnPc decreased while the triplet quantum yields increased in the presence of MF. For (Cl)AlPc, the triplet lifetimes were found to increase with decrease in laser energy while there was photoreduction to the Pc−3 species. Singlet oxygen and photodegradation quantum yields decreased in the presence of MF, suggesting quenching.
- Full Text:
- Date Issued: 2007
- Authors: Idowu, Mopelola , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281298 , vital:55710 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.12.013"
- Description: The effect of magnetic fluid (MF) on the photophysical and photochemical parameters of zinc and aluminum phthalocyanines are reported. The complexes studied are zinc (II) phthalocyanine (ZnPc), chloroaluminum phthalocyanine ((Cl)AlPc) and tetrasulfonated aluminum phthalocyanine ((Cl)AlTSPc). The parameters are studied in dimethylsulfoxide (DMSO) for all complexes and also in aqueous media for (Cl)AlTSPc. The triplet lifetimes for (Cl)AlTSPc and ZnPc decreased while the triplet quantum yields increased in the presence of MF. For (Cl)AlPc, the triplet lifetimes were found to increase with decrease in laser energy while there was photoreduction to the Pc−3 species. Singlet oxygen and photodegradation quantum yields decreased in the presence of MF, suggesting quenching.
- Full Text:
- Date Issued: 2007
Photophysical and photochemical studies of long chain-substituted zinc phthalocyanines
- Durmus, Mahmut, Ahsen, Vefa, Nyokong, Tebello
- Authors: Durmus, Mahmut , Ahsen, Vefa , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281310 , vital:55711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.08.025"
- Description: Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetra(13,17-dioxanonacosane-15-hydroxy)-substituted zinc phthalocyanines (1, 2). General trends are described for quantum yields of photodegradation, fluorescence yields, triplet lifetimes and triplet quantum yields as well as singlet quantum yields of these compounds in dimethylformamide (DMF) and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2) are reported.
- Full Text:
- Date Issued: 2007
- Authors: Durmus, Mahmut , Ahsen, Vefa , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281310 , vital:55711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.08.025"
- Description: Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetra(13,17-dioxanonacosane-15-hydroxy)-substituted zinc phthalocyanines (1, 2). General trends are described for quantum yields of photodegradation, fluorescence yields, triplet lifetimes and triplet quantum yields as well as singlet quantum yields of these compounds in dimethylformamide (DMF) and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2) are reported.
- Full Text:
- Date Issued: 2007
Photophysical, photochemical and bovine serum albumin binding studies on water-soluble gallium (III) phthalocyanine derivatives
- Ogunsipe, Abimbola, Nyokong, Tebello, Durmus, Mahmut
- Authors: Ogunsipe, Abimbola , Nyokong, Tebello , Durmus, Mahmut
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271239 , vital:54524 , xlink:href="https://doi.org/10.1142/S1088424607000746"
- Description: Spectral, photophysical, photochemical and bovine serum albumin binding studies on some gallium(III) derivatives - {1,(4)-(tetrapyridyloxyphthalocyaninato)gallium(III), (αGaPc); 2,(3)-(tetrapyridyloxyphthalocyaninato)gallium(III), (βGaPc); and their quaternized derivatives: QαGaPc and QβGaPc)} are hereby presented. β-Substituted complexes are more fluorescent, but show lower tendencies to undergo intersystem crossing than the α-substituted, as judged by their fluorescence and triplet quantum yield values. The quaternized derivatives (QGaPc) are water-soluble and non-aggregated, which makes them potential photosensitizers of choice for photodynamic therapy applications; these amphiphilic compounds also bind strongly to bovine serum albumin in 1:1 stoichiometries, and with binding constants (Kb) in the order of 106 M−1.
- Full Text:
- Date Issued: 2007
- Authors: Ogunsipe, Abimbola , Nyokong, Tebello , Durmus, Mahmut
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271239 , vital:54524 , xlink:href="https://doi.org/10.1142/S1088424607000746"
- Description: Spectral, photophysical, photochemical and bovine serum albumin binding studies on some gallium(III) derivatives - {1,(4)-(tetrapyridyloxyphthalocyaninato)gallium(III), (αGaPc); 2,(3)-(tetrapyridyloxyphthalocyaninato)gallium(III), (βGaPc); and their quaternized derivatives: QαGaPc and QβGaPc)} are hereby presented. β-Substituted complexes are more fluorescent, but show lower tendencies to undergo intersystem crossing than the α-substituted, as judged by their fluorescence and triplet quantum yield values. The quaternized derivatives (QGaPc) are water-soluble and non-aggregated, which makes them potential photosensitizers of choice for photodynamic therapy applications; these amphiphilic compounds also bind strongly to bovine serum albumin in 1:1 stoichiometries, and with binding constants (Kb) in the order of 106 M−1.
- Full Text:
- Date Issued: 2007
Realistic idealism
- Authors: Tabensky, Pedro
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/305700 , vital:58605 , xlink:href="https://doi.org/10.3167/th.2007.5411306"
- Description: Realists found in International Relations (IR) circles explicitly assign relatively minor importance to ethical ideals in their analyses of the international political domain, although a robust ethical ideal of sorts, implicitly for the most part qua ethical ideal, does guide their analysis of the international arena. For them, the key to order in the international arena is the balance of power reached between different nations aiming at asserting their wills, promoting their interests, in what is in effect perceived by IR realists as an international battle of wills guided primarily by the logic of power. As a purely descriptive claim regarding how nations, for the most part, actually behave, I have no axe to grind with the IR realist, or at least I do not have to grind an axe with them on this matter for the purposes of this paper, but the IR realist is committed to more than merely describing the behaviour of the international order. IR realists, implicitly and paradoxically, are forced, by the logic of their own position, to believe that the ethical ideal that ought to be guiding the international order is the balance of power between competing interests guiding the international behaviour of nations in their quest for power and (alleged) survival. The primary moral dictum of their position is that nations ought to pursue their self-interested interests relentlessly, but only to the extent that the fragile balance of power is not upset (which is, at any rate, a central ingredient for promoting national self-interest). IR realists do not altogether explicitly deny the role of ideals, but the role they assign to ideals is limited and, I will argue, ultimately incoherent, for ideals ought to be understood as flowing from the structure of our embodied existences and into every nook and cranny of our lives, understood individually and collectively, nationally and internationally. We are active creatures, as Aristotle observed, and activities are defined as such in relation to a functional ideal, an ideal of operation, which flows from our specific modes of embodiment. The norms or ends guiding the international political order ought to flow from this understanding of the human subject ideally conceived, as opposed to the largely Machiavellian pessimistic understanding of the human situation informing IR realism; a pessimism that stems from the fallacious move from raw observation to normative recommendation. To claim that our ends are Machiavellian, we shall see, is incoherent and this incoherence is at the heart of IR realism. The demands of reason, we shall see, should push us in the direction of a particular variety of optimism. By using a broadly Aristotelian teleological technique of analysis I will show that IR realists cannot be right. Without placing ideals at the centre of our understandings of our political lives we would be unable properly to understand the political domain, including the specific sphere of concern of IR specialists. The purely observational descriptions alluded to above do not provide the grounds for proper understanding. What does provide a proper understanding, we shall see, is observation through a conceptual lens informed by a teleological understanding of the human person (observation in the light of a conception of the good). That I think a robust conception of the good, of the set of ideals that out to be guiding rational human life, is necessary for properly understanding the international arena does not of course mean that I advocate any such conception of the good. As claimed above, the sort that I advocate, following Aristotle’s footsteps, flows from the specific configuration of our embodied lives. I refer to this form of idealism as realistic idealism.
- Full Text:
- Date Issued: 2007
- Authors: Tabensky, Pedro
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/305700 , vital:58605 , xlink:href="https://doi.org/10.3167/th.2007.5411306"
- Description: Realists found in International Relations (IR) circles explicitly assign relatively minor importance to ethical ideals in their analyses of the international political domain, although a robust ethical ideal of sorts, implicitly for the most part qua ethical ideal, does guide their analysis of the international arena. For them, the key to order in the international arena is the balance of power reached between different nations aiming at asserting their wills, promoting their interests, in what is in effect perceived by IR realists as an international battle of wills guided primarily by the logic of power. As a purely descriptive claim regarding how nations, for the most part, actually behave, I have no axe to grind with the IR realist, or at least I do not have to grind an axe with them on this matter for the purposes of this paper, but the IR realist is committed to more than merely describing the behaviour of the international order. IR realists, implicitly and paradoxically, are forced, by the logic of their own position, to believe that the ethical ideal that ought to be guiding the international order is the balance of power between competing interests guiding the international behaviour of nations in their quest for power and (alleged) survival. The primary moral dictum of their position is that nations ought to pursue their self-interested interests relentlessly, but only to the extent that the fragile balance of power is not upset (which is, at any rate, a central ingredient for promoting national self-interest). IR realists do not altogether explicitly deny the role of ideals, but the role they assign to ideals is limited and, I will argue, ultimately incoherent, for ideals ought to be understood as flowing from the structure of our embodied existences and into every nook and cranny of our lives, understood individually and collectively, nationally and internationally. We are active creatures, as Aristotle observed, and activities are defined as such in relation to a functional ideal, an ideal of operation, which flows from our specific modes of embodiment. The norms or ends guiding the international political order ought to flow from this understanding of the human subject ideally conceived, as opposed to the largely Machiavellian pessimistic understanding of the human situation informing IR realism; a pessimism that stems from the fallacious move from raw observation to normative recommendation. To claim that our ends are Machiavellian, we shall see, is incoherent and this incoherence is at the heart of IR realism. The demands of reason, we shall see, should push us in the direction of a particular variety of optimism. By using a broadly Aristotelian teleological technique of analysis I will show that IR realists cannot be right. Without placing ideals at the centre of our understandings of our political lives we would be unable properly to understand the political domain, including the specific sphere of concern of IR specialists. The purely observational descriptions alluded to above do not provide the grounds for proper understanding. What does provide a proper understanding, we shall see, is observation through a conceptual lens informed by a teleological understanding of the human person (observation in the light of a conception of the good). That I think a robust conception of the good, of the set of ideals that out to be guiding rational human life, is necessary for properly understanding the international arena does not of course mean that I advocate any such conception of the good. As claimed above, the sort that I advocate, following Aristotle’s footsteps, flows from the specific configuration of our embodied lives. I refer to this form of idealism as realistic idealism.
- Full Text:
- Date Issued: 2007